Fig 3. Muscle fiber cross-section area and frequency distribution.

(A) There was no difference in myofiber CSA between the groups (p = 0.72). Young (n = 9 mice, 1433 muscle fibers measured) and aged mice (n = 9 mice, 893 muscle fibers measured). Data shown as mean ± standard deviation. (B) However, there is a decrease in muscle fiber size heterogeneity in the aged mice as compared to the young animals as evidenced by a narrowing of the frequency distribution for aged mice.